Wind energy is used to drive a wind turbine, which is in turn connected to an electrical generator to produce electrical power. The pitch angle of the wind turbine blades is controlled in a closed loop manner to maintain either a constant generator speed for isolated power generating stations or whe ...

A multi-mode electronic wind turbine control system establishes a reference blade angle for a two-bladed, horizontal axis, variable pitch wind turbine rotor, the blade angle being regulated by a hydraulic pitch change mechanism. The rotor, via appropriate shafts and a gearbox, is coupled to a synchr ...

A power generating system includes a wind turbine driven generator, the wind turbine having a wind turbine driven rotor with a variable pitch angle blade. Stresses on the system during startup and shutdown are minimized by scheduling the blade angle as a function of the rotor speed and wind velocity ...

A power generating system includes a wind turbine driven generator, the wind turbine having a wind driven rotor with a plurality of variable pitch angle blades. The blade angle is scheduled during acceleration and deceleration of the wind turbine by open loop controls to minimize stresses, and is sc ...

Surface acoustic waves are propagated across a thin, flexible diaphragm which is subjected to an applied external pressure. Since the wave velocity and path length vary with diaphragm deformation, the acoustic wave delay time is a function of the applied external pressure. Electroacoustic transducer ...

The contaminants in the exhaust gas emissions from a motor vehicle such as carbon monoxide (CO) and hydrocarbons (HC) are analyzed within a nondispersive infrared analyzer which includes means for assuring that the vehicle being tested has achieved a predetermined engine speed and that no blockage h ...

The contaminants in the exhaust gas emissions from a motor vehicle such as carbon monoxide (CO) and hydrocarbons (HC) are analyzed and the concentration of the contaminants together with other pertinent data is displayed in a digital manner. The exhaust gas emissions are fed into a sample cell conta ...

In an air conditioning system for a load, air is used as the refrigerant, and identical components including a turbocompressor and a regenerative heat exchanger are used for both cooling in the refrigeration mode and heating in the heat pump mode. A plurality of valves are arranged so that in the re ...

A cover for nursery and flower pots is constructed from a thin flexible plastic material having a plurality of holes therein through which water and nutrients may be supplied to the stock. A circumferential lip about the outside perimeter of the cover is adapted to fit over the top of a pot and secu ...

In a fluid pumping system in which a fluid is pumped from a fluid supply to a load, two continuously driven fixed displacement pumps are operated in parallel to provide the pumping action. The two pumps are arranged with a common inlet, and with a common outlet, the flow delivered to the load from o ...